The invention relates to a novel sweetener, to a process for the preparation thereof and to the use of this sweetener in foodstuffs and other consumables.
Since sucrose is a high-calorie foodstuff, promotes dental caries and is unsuitable for diabetics, there is a need for other sweeteners which, in contrast to synthetic sweetening substances such as saccharin, cyclamate or aspartame, have no additional taste and have bodying properties.
Sweeteners which have been proposed to date as non-cariogenic, low-calorie sweeteners are, inter alia, maltitol and lactitol as well as isomaltitol. The former have only limited uses because of their syrupy consistency, while the latter has not to date been prepared in an economic manner.
Isomaltitol can be obtained, for example, as described in DE 22 17 628 A1 via isomaltulose as intermediate with subsequent catalytic hydrogenation. The yield of the intermediate isomaltulose is only 45%, and the overall yield of isomaltitol is 41%.
Although according to EP 28 900 A1, EP 49 472 A1 and EP 91 063 A1 it is possible with immobilized bacterial cells to bring about enzymatic conversion of sucrose into isomaltulose in a yield of about 80%, purified isomaltulose is required to prepare isomaltitol so that in this process a reduction in yield also occurs due to crystallization.
Furthermore, isomaltitol has the disadvantage that, because of its low solubility, it tends to crystallize out in food products which leads, for example, to chocolate having a sandy taste, hard candies becoming cloudy and crystals forming in jams.
Furthermore, DE 25 20 173 A1 discloses that catalytic reduction of isomaltulose in neutral aqueous solution results not only in isomaltitol, that is to say glucopyranosyl-1,6-sorbitol (=1,6-GPS), but also in the stereoisomeric glucopyranosyl-1, 6-mannitol (=1, 6-GPM) up to a ratio of 1:1 by weight. It is true that 1,6-GPM can,. because of its low solubility, be easily isolated and is, as a low-calorie, bodying product, an enrichment of dietetics. However, because of its low solubility it crystallizes out in food products even more readily than isomaltitol and must--because the sweetening power is only about 40% that of sucrose--be employed in a larger amount to achieve the same sweetening effect.
Mixtures of 1,6-GPS or 1,6-GPM with other sugar alcohols or sugars also yield unsatisfactory products. Even on use of sorbitol, which is known to suppress crystallization, the resulting products are hygroscopic, that is to say sticky.
Finally, EP 109 009 A1 describes an isomerization product which was prepared from sucrose with Protaminobacter rubrum (CBS 574.77) and has the following composition by weight of DM (dry matter) content:
______________________________________ Fructose 5-8% by weight of DM content Glucose 2-5% by weight of DM content Sucrose 0-0.5% by weight of DM content Isomaltulose 65-72% by weight of DM content Trehalulose 10-20% by weight of DM content Oligomers 3-6% by weight of DM content ______________________________________
A saccharide mixture of this type is unsuitable as dietetic sweetener because some components are utilized calorically, show insulin-dependent metabolism and promote dental caries. It is true that the trehalulose content can be increased to 35% if the sugar mixture is kept with free or carrier-immobilized bacterial cells under suitable conditions for about 100 h. However, this process is uneconomic.
The invention is therefore based on the object of proposing a sweetener and a process for the preparation of a novel low-calorie, non-cariogenic sweetener which is suitable for diabetics and which combines a pleasant sweetening effect with good bodying properties, can be prepared in solid form easily and economically and does not crystallize out in the concentrations used.